Solar Magnetized “Tornadoes:” Relation to Filaments

Su, Yang; Wang, Tongjiang; Veronig, Astrid; Temmer, Manuela; Gan, Weiqun

doi:10.1088/2041-8205/756/2/l41

Cited by 96 publications

(117 citation statements)

References 34 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…Magnetic tubes near the solar photosphere, chromosphere, and corona can be twisted for various reasons: during the rising phase along the convection zone (Moreno-Insertis & Emonet 1996; Archontis et al 2004;Murray & Hood 2008;Hood et al 2009), by sunspot rotations (Khutsishvili et al 1998;Brown et al 2003;Yan & Qu 2007;Zhang et al 2007), and/or by magnetic tornadoes in the chromosphere and the corona (Wedemeyer-Böhm et al 2012;Su et al 2012;Li et al 2012). Solar prominences are also supposed to be formed in a twisted magnetic field (Priest et al 1989).…”

Section: Discussionmentioning

confidence: 99%

“…The observed rotation of sunspots (Khutsishvili et al 1998;Brown et al 2003;Yan & Qu 2007;Zhang et al 2007) may lead to the twisting of the magnetic field above active regions, which can be observed as twisted loops in the corona (Srivastava et al 2010). Recent observations of magnetic tornados (Wedemeyer-Böhm et al 2012;Su et al 2012;Li et al 2012) also strongly support the existence of twisted magnetic flux tubes on the Sun. Newly emerged magnetic tubes can also be twisted in the convection zone during the rising phase (Moreno-Insertis & Emonet 1996; Archontis et al 2004;Murray & Hood 2008;Hood et al 2009).…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Kelvin-Helmholtz instability of twisted magnetic flux tubes in the solar wind

Zaqarashvili

Vörös

Zhelyazkov

2013

A&A

View full text Add to dashboard Cite

Context. Tangential velocity discontinuity near the boundaries of solar wind magnetic flux tubes results in Kelvin-Helmholtz instability, which might contribute to solar wind turbulence. While the axial magnetic field stabilizes the instability, a small twist in the magnetic field may allow sub-Alfvénic motions to be unstable. Aims. We aim to study the Kelvin-Helmholtz instability of twisted magnetic flux tubes in the solar wind with different configurations of the external magnetic field. Methods. We use magnetohydrodynamic equations in cylindrical geometry and derive the dispersion equations governing the dynamics of twisted magnetic flux tubes moving along its axis in the cases of untwisted and twisted external fields. Then, we solve the dispersion equations analytically and numerically and find thresholds for Kelvin-Helmholtz instability in both cases of the external field.Results. Both analytical and numerical solutions show that the Kelvin-Helmholtz instability is suppressed in the twisted tube by the external axial magnetic field for sub-Alfvénic motions. However, even a small twist in the external magnetic field allows the Kelvin-Helmholtz instability to be developed for any sub-Alfvénic motion. The unstable harmonics correspond to vortices with high azimuthal mode numbers that are carried by the flow. Conclusions. Twisted magnetic flux tubes can be unstable to Kelvin-Helmholtz instability when they move with small speed relative to the main solar wind stream, then the Kelvin-Helmholtz vortices may significantly contribute to the solar wind turbulence.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Kelvin-Helmholtz instability of twisted magnetic flux tubes in the solar wind

Zaqarashvili

Vörös

Zhelyazkov

2013

A&A

View full text Add to dashboard Cite

show abstract

“…Through observations of the Atmospheric Imaging Assembly (AIA, Lemen et al 2011) on board SDO, Li et al (2012) found the formation of a solar tornado and its relationship with the coronal cavity above. Su et al (2012) found that the rotating solar tornadoes observed with SDO/AIA have a connection with prominences. The pos-sible relationship between a solar tornado and CMEs/flares from the surrounding active region has also been reported (Panesar et al 2013).…”

Section: Introductionmentioning

confidence: 92%

Two Solar Tornadoes Observed with the Interface Region Imaging Spectrograph

Yang

Tian

Peter

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

The barbs or legs of some prominences show an apparent motion of rotation, which are often termed solar tornadoes. It is under debate whether the apparent motion is a real rotating motion, or caused by oscillations or counter-streaming flows. We present analysis results from spectroscopic observations of two tornadoes by the Interface Region Imaging Spectrograph. Each tornado was observed for more than 2.5 hours. Doppler velocities are derived through a single Gaussian fit to the Mg ii k 2796Å and Si iv 1393Å line profiles. We find coherent and stable redshifts and blueshifts adjacent to each other across the tornado axes, which appears to favor the interpretation of these tornadoes as rotating cool plasmas with temperatures of 10 4 K-10 5 K. This interpretation is further supported by simultaneous observations of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, which reveal periodic motions of dark structures in the tornadoes. Our results demonstrate that spectroscopic observations can provide key information to disentangle different physical processes in solar prominences.

show abstract

“…This work aims to provide an insight into the physical conditions found in the so-called large-scale solar tornadoes that have been observed in the legs of prominences (Wedemeyer et al 2013). There is an ongoing debate about how to interpret the apparent rotation of these features (see Orozco Suárez et al 2012;Li et al 2012;Su et al 2012Su et al , 2014Panesar et al 2013). Clearly, combining high-resolution images, spectroscopic observations, and magnetic field measurements is the best approach to making any progress in this discussion.…”

Section: Introductionmentioning

confidence: 99%

A solar tornado observed by EIS

Levens

Labrosse

Fletcher

et al. 2015

A&A

View full text Add to dashboard Cite

Context. The term "solar tornadoes" has been used to describe apparently rotating magnetic structures above the solar limb, as seen in high resolution images and movies from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). These often form part of the larger magnetic structure of a prominence, however the links between them remain unclear. Here we present plasma diagnostics on a tornado-like structure and its surroundings, seen above the limb by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard the Hinode satellite. Aims. We aim to extend our view of the velocity patterns seen in tornado-like structures with EIS to a wider range of temperatures and to use density diagnostics, non-thermal line widths, and differential emission measures to provide insight into the physical characteristics of the plasma. Methods. Using Gaussian fitting to fit and de-blend the spectral lines seen by EIS, we calculated line-of-sight velocities and nonthermal line widths. Along with information from the CHIANTI database, we used line intensity ratios to calculate electron densities at each pixel. Using a regularised inversion code we also calculated the differential emission measure (DEM) at different locations in the prominence. Results. The split Doppler-shift pattern is found to be visible down to a temperature of around log T = 6.0. At temperatures lower than this, the pattern is unclear in this data set. We obtain an electron density of log n e = 8.5 when looking towards the centre of the tornado structure at a plasma temperature of log T = 6.2, as compared to the surroundings of the tornado structure where we find log n e to be nearer 9. Non-thermal line widths show broader profiles at the tornado location when compared to the surrounding corona. We discuss the differential emission measure in both the tornado and the prominence body, which suggests that there is more contribution in the tornado at temperatures below log T = 6.0 than in the prominence.

show abstract

Solar Magnetized “Tornadoes:” Relation to Filaments

Abstract: Solar magnetized "tornadoes", a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but root in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized

Cited by 96 publications

References 34 publications

Kelvin-Helmholtz instability of twisted magnetic flux tubes in the solar wind

Kelvin-Helmholtz instability of twisted magnetic flux tubes in the solar wind

Two Solar Tornadoes Observed with the Interface Region Imaging Spectrograph

A solar tornado observed by EIS

Contact Info

Product

Resources

About